Description: Trees or shrubs, some species deciduous, either unarmed or with prickles or spines.
Leaves alternate, bipinnate; pinnae usually 1 or 2 pairs; pinnules usually numerous, entire margins, jugary glands small, rarely absent; stipules usually spinescent, straight, [or absent].
Inflorescences axillary, spike-like racemes or dense spikes, shorter or longer than the leaves. Flowers bisexual, 5-merous, greenish yellow. Calyx 5-toothed, shorter than petals. Petals fused in lower half. Stamens 10, free, much longer than petals. Ovary pubescent.
Pod linear, usually ± moniliform, thick and compressed, not dehiscent, usually flattened when immature; seeds compressed-ovoid, hard, smooth.
Distribution and occurrence: World: c. 40 species, warmer parts of North & South America, Asia & Africa. Australia: at least 5 species (naturalized), Qld., N.S.W., S.A., W.A.
Species were introduced to western N.S.W. as garden ornamentals and for soil stabilization. They have invaded arid pasture land and become established along drainage lines and are proving difficult to eradicate.
Text by L. Murray Taxon concept:
| Key to the species | |
1 | Spines usually solitary; leaflets 25–45 mm long. | Prosopis glandulosa |
| Spines paired; leaflets 4–12 mm long. | 2 |
2 | Leaves with 1 or 2 pairs of pinnae; pod with undulate margins regularly constricted between the seeds, velvety when young. | Prosopis velutina |
| Leaves with 2–4 pairs of pinnae; pod with margins parallel or slightly undulate, glabrous. Back to 1 | Prosopis pallida |
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